SQLite

** Information and control of an open file handle.
*/
static int unixFileControl(sqlite3_file *id, int op, void *pArg){
  switch( op ){
    case SQLITE_FCNTL_LOCKSTATE: {
      *(int*)pArg = ((unixFile*)id)->locktype;
      return SQLITE_OK;
    }
    case SQLITE_FCNTL_SIZE_HINT: {
      sqlite3_int64 szFile = *(sqlite3_int64*)pArg;
      unixFile *pFile = (unixFile*)id;
      ftruncate(pFile->h, szFile);
      return SQLITE_OK;
    }
  }
  return SQLITE_ERROR;
}

/*
** Return the sector size in bytes of the underlying block device for

** every one of those pages out to the database file and mark them all
** as clean.
*/
static int pager_write_pagelist(PgHdr *pList){
  Pager *pPager;
  PgHdr *p;
  int rc;
  sqlite3_int64 szFile;          /* Final size of databsae file */

  if( pList==0 ) return SQLITE_OK;
  pPager = pList->pPager;

  /* At this point there may be either a RESERVED or EXCLUSIVE lock on the
  ** database file. If there is already an EXCLUSIVE lock, the following
  ** calls to sqlite3OsLock() are no-ops.

  }

  pList = sort_pagelist(pList);
  for(p=pList; p; p=p->pDirty){
    assert( p->dirty );
    p->dirty = 0;
  }
  szFile = pPager->pageSize * (sqlite3_int64)pPager->dbSize;
  while( pList ){

    /* If the file has not yet been opened, open it now. */
    if( !pPager->fd->pMethods ){
      assert(pPager->tempFile);
      rc = sqlite3PagerOpentemp(pPager, pPager->fd, pPager->vfsFlags);
      if( rc ) return rc;
    }

    /* Before the first write, give the VFS a hint of what the final
    ** file size will be.
    */
    if( szFile>0 ){
      sqlite3OsFileControl(pPager->fd, SQLITE_FCNTL_SIZE_HINT, &szFile);
      szFile = 0;
    }

    /* If there are dirty pages in the page cache with page numbers greater
    ** than Pager.dbSize, this means sqlite3PagerTruncate() was called to
    ** make the file smaller (presumably by auto-vacuum code). Do not write
    ** any such pages to the file.
    */
    if( pList->pgno<=pPager->dbSize ){

** The [SQLITE_FCNTL_LOCKSTATE] opcode is used for debugging.  This
** opcode causes the xFileControl method to write the current state of
** the lock (one of [SQLITE_LOCK_NONE], [SQLITE_LOCK_SHARED],
** [SQLITE_LOCK_RESERVED], [SQLITE_LOCK_PENDING], or [SQLITE_LOCK_EXCLUSIVE])
** into an integer that the pArg argument points to. This capability
** is used during testing and only needs to be supported when SQLITE_TEST
** is defined.
**
** The [SQLITE_FCNTL_SIZE_HINT] opcode is used by SQLite to give the VFS
** layer a hint of how large the database file will grow to be during the
** current transaction.  This hint is not guaranteed to be accurate but it
** is often close.  The underlying VFS might choose to preallocate database
** file space based on this hint in order to help writes to the database
** file run faster.
*/
#define SQLITE_FCNTL_LOCKSTATE        1
#define SQLITE_FCNTL_SIZE_HINT        2

/*
** CAPI3REF: Mutex Handle {H17110} <S20130>
**
** The mutex module within SQLite defines [sqlite3_mutex] to be an
** abstract type for a mutex object.  The SQLite core never looks
** at the internal representation of an [sqlite3_mutex].  It only

       db close
       file delete -force test.db
       sqlite3 db test.db
       db eval "PRAGMA auto_vacuum=OFF"
       db eval "PRAGMA page_size=$pagesize"
       db eval {CREATE TABLE t1(x)}
       file size test.db
     } [expr {$pagesize*2<$sqlite_pending_byte ? $pagesize*2 : $pagesize*3}]
     do_test filefmt-1.5.$pagesize.2 {
       hexio_get_int [hexio_read test.db 16 2]
     } $pagesize
  }
}

# The page-size must be a power of 2

      INSERT INTO abc SELECT * FROM abc;
      INSERT INTO abc SELECT * FROM abc;
      INSERT INTO abc SELECT * FROM abc;
    }
    # File has grown - showing there was a cache-spill - but there 
    # have been no calls to fsync():
    list [file size test.db] [nSync]
  } {38912 0}
  do_test io-3.3 {
    # The COMMIT requires a single fsync() - to the database file.
    execsql { COMMIT }
    list [file size test.db] [nSync]
  } {39936 1}
}